Single and multi-dose pharmacokinetics of zimelidine have been evaluated. Early data analysis in 4 patients (elderly) indicates that system's linearity is maintained for zimelidine and steady-state plasma concentrations can be predicted from single-dose. However multi-dose Nor-zimelidine levels may show significant variation when predicted based on single dose data. This indicates that the active metabolite "Norzimeldine" may show a tendency to accumulate and dosing adjustments may be necessary for elderly population.